Susceptibility testing and bactericidal activities of Theobroma cacao Linn. (cocoa) on Helicobacter pylori in an in vitro study

The in vitro anti-Helicobacter pylori properties of n-hexane and methanol extracts of the dried seeds of Theobroma cacao Linn. were investigated in forty-one (41) Helicobacter pylori (H. pylori) clinical isolates collected from a cross-section of residents living in Oyo State, Nigeria and standard H. pylori ATCC 43504 strains. Phytochemical screening was carried out on the extracts to detect the presence of secondary metabolites. The extracts were tested against the H. pylori strains using the agar well diffusion method at varying concentrations (≤100 mg/mL). The minimum inhibitory concentration (MIC) of the crude extracts was determined against the susceptible strains by the agar dilution method. Bactericidal (kill-kinetics) studies were further carried out on two H. pylori clinical isolates. The methanol extracts of T. cacao L. (cocoa) seed had an inhibitory effect against H. pylori strains to a varying degree; with diameter zones of inhibition between 12 mm and 17 mm on 31 out of the 41 clinical isolates tested with MIC values of 80 to 90 mg/mL. The time–kill study of the methanol extract on H. pylori BAA009 and H. pylori BAA026, revealed a decline in the surviving population after 8 h of exposure at doses equivalent to MIC, 2× MIC and 4× MIC, accompanied with a total kill of the population at 24 h.From this study it may be concluded that regular consumption of T. cacao L. (cocoa) seed or its products in Nigeria and other developing countries where the plant is cultivated could greatly reduce the incidence of peptic ulcer, as well as suppress acute and chronic gastrointestinal inflammation caused by H. pylori a common gastric pathogen.